2. Iran’s Supreme Leader Ayatollah Ali Khamenei called for divine revenge against Saudi Arabia and Iranian citizens attacked the Saudi embassy in Iran, setting it on fire with molotov cocktails.

3. Saudi Arabia severed diplomatic ties with Iran, expelling all of their diplomats from the country and canceling all air flights between the two countries.

4. Several countries with ties to Saudi Arabia (Bahrain, United Arab Emirates and Sudan) have followed suit, recalling diplomats from Iran.

This is an extremely complicated situation with roots in the domestic and foreign affairs of both countries. On the former, here is a quick look:

“There are domestic reasons for both of these countries right now to refuse to pull punches against each other,” said Ian Bremmer, president of the Eurasia Group consulting firm.

Saudi Arabia, he said, is dealing with plummeting oil prices and an internal succession battle over who will next take the throne.

Iran, he said, needs a way to block reformists and Western advances in light of the recent nuclear deal. For both sides, he said, nationalist behavior can score points at home.

When it comes to the foreign affairs issues, it might be helpful to start by defining what we call “proxy wars.”

A proxy war is a conflict between two nations where neither country directly engages the other. While this can encompass a breadth of armed confrontation, its core definition hinges on two separate powers utilizing external strife to somehow attack the interests or territorial holdings of the other. This frequently involves both countries fighting their opponent’s allies, or assisting their allies in fighting their opponent.

In the Middle East, regardless of whether we are talking about the battles in Syria, Yemen, Iraq, Lebanon or elsewhere, they can all be viewed not only as conflicts within the country, but as proxy wars between Saudi Arabia and Iran. Outwardly, they are all part of the centuries-old battle between Sunni (Saudi Arabia) and Shia (Iran). But, as with most religious conflicts, it really come down to a battle for power and control.

Into that mix, President Obama has introduced a different vision. Here’s how he described it to David Remnick a year ago:

Ultimately, he envisages a new geopolitical equilibrium, one less turbulent than the current landscape of civil war, terror, and sectarian battle. “It would be profoundly in the interest of citizens throughout the region if Sunnis and Shias weren’t intent on killing each other,” he told me. “And although it would not solve the entire problem, if we were able to get Iran to operate in a responsible fashion—not funding terrorist organizations, not trying to stir up sectarian discontent in other countries, and not developing a nuclear weapon—you could see an equilibrium developing between Sunni, or predominantly Sunni, Gulf states and Iran in which there’s competition, perhaps suspicion, but not an active or proxy warfare.

In other words, the President is attempting to introduce an alternative to the zero-sum game that has consumed these Middle East conflicts. Now that the Iranian nuclear deal has been reached, Marc Lynch describes how Saudi Arabia is reacting.

The Saudi escalation is above all driven by its fear of the potential success of the U.S. deal with Iran over its nuclear weapons program. Saudi Arabia views Iran’s reintegration into the international order and its evolving relationship with Washington as a profound threat to its own regional position…The sectarian escalation likely is meant to undermine America’s primary strategic objectives in the region such as the Iran deal and a negotiated end to the Syria war by inflaming tensions in ways that make diplomatic progress impossible.

Remember when President Obama suggested that the Republicans who opposed the Iranian nuclear deal had something in common with the hard-liners in Iran? He said that they were both interested in hanging on to the “status quo.” We can now officially add Saudi Arabia to the group that is doing what it can to maintain the status quo of a Middle East engulfed in proxy wars. And it should come as no surprise that Republican presidential candidates are weighing in to support them in that.